Method and apparatus for immersion treatment of semiconductor and other devices

ABSTRACT

Method and apparatus for cleaning semiconductor devices and other workpieces using an aqueous rinse solution which is de-oxygenated by passing the aqueous rinse solution and a carrier gas through an osmotic membrane degasifier. A cleaning chamber is also disclosed for carrying out the cleaning method.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention pertains to the aqueous processing ofvarious articles, including the immersion cleaning of semiconductorwafers, using deoxygenated aqueous rinse solutions.

[0003] 2. Description of the Related Art

[0004] As will be seen herein, the present invention is directed to theaqueous treatment of a wide variety of commercially important articles,such as liquid crystal displays, flat panel displays, memory storagedisk substrates, as well as photographic plates and film. The presentinvention has found immediate commercial acceptance in the field ofsemiconductor wafers, especially wafers of a type which are ultimatelydivided to form a plurality of electronic devices.

[0005] During the course of producing commercial semiconductor wafers,layers of various materials are built up on one surface of a waferblank. These various layers are processed using several differentetching techniques, each of which results in a residue which impairsfurther device fabrication. It is important that such residues beeffectively removed. Typically, the several types of residue are removedwith solvents especially adapted for the particular residues. While suchsolvents are generally effective for removing residues, solventsremaining on the surfaces of the semiconductor device also impairfurther device fabrication steps.

[0006] Accordingly, it is important that the solvents be removed fromthe semiconductor device and it is known that water rinsing is anefficient means of solvent removal. However, semiconductor device layermaterials have changed over the years, and presently semiconductordevice manufacturers are employing materials which are subject tocorrosion upon contact with water. In an effort to reduce the corrosionproblem, carbon dioxide gas has been sparged, i.e., bubbled, into therinse water to partially lower the pH of the rinse water. However,bubbling carbon dioxide into water rinses used in the semiconductordevice fabrication industry has proven to be only marginally successfulin reducing the extent of corrosion, and further adds the risk ofintroducing contaminating particles into solution. In an effort toovercome growing problems of corrosion, the semiconductor devicefabrication industry has investigated intermediate rinse steps usingnon-aqueous rinse solutions. However, such non-aqueous solutions haveproven to be less effective than rinse water in removing solvents andwafers are still routinely rinsed with water, despite the corrosioneffects.

[0007] Significant efforts have been expended in reducing the amount ofexposure of a wafer containing alloys of copper and aluminum to rinsewater. However, it appears that, in order to meet future requirementsfor improved electrical performance, the aluminum content of the alloymust be substantially reduced and possibly eliminated, thussubstantially increasing the susceptibility of the wafer layer materialsto corrosion, at higher levels than those presently experienced.

[0008] One example of efforts to improve wafer production involvesoxygen removal to reduce oxide growth on the surface of semiconductorwafers. For example, literature describing the PALL SEPAREL ModelEFM-530 Degasification Module addresses the reduction of dissolvedoxygen in deionized water, in a manner which avoids potential defects tosemiconductor devices caused by the formation of unwanted oxide layers.As is known in the art, an oxide layer forms when pure silicon isexposed to an oxygen source, such as dissolved oxygen in a rinse wateror other aqueous medium. The oxide layer can change the surface of thesilicon from hydrophobic to hydrophilic, a condition which isundesirable in some aspects of wafer processing, such as pre-diffusioncleaning operations. Accordingly, the PALL Degasification Moduleaddresses the need to deoxygenate rinse water to avoid formation of asilicon dioxide layer in the rinse after the wafer is treated with an HFetch solution. As can be seen, the problem addressed by the PALLDegasification Module is not related to problems encountered incontrolling corrosion of aluminum, such as pitting and etching, as hasbeen experienced in processing wafers carrying copper/aluminumstructures on their surface. While dissolved oxygen is alsoobjectionable from a corrosion standpoint, the corrosion problem is notconcerned with the formation of unwanted oxides. A further, morecomplete system control over wafer processing so as to reduce corrosionin wafers containing copper/aluminum structures is needed.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide cleaning forsemiconductor wafers using aqueous solutions which are treated in amanner to eliminate corrosion of semiconductor device materials layeredon semiconductor substrates.

[0010] Another object of the present invention is to provide cleaning ofthe above-described type which is effective even in relatively small,hollow structures formed in a semiconductor surface, such as vias.

[0011] A further object of the present invention is to provide aqueoustreatment of the type described above which removes dissolved oxygenfrom an aqueous solution while controlling the pH of the aqueoussolution.

[0012] Another object of the present invention is to providearrangements for aqueous treatment of many different types of devicesusing conventional readily obtained equipment, and consumables which arerelatively inexpensive.

[0013] Yet another object of the present invention is to provide processarrangements of the type described above by employing an osmoticmembrane degasifier and using a carrier fluid (preferably a gas)comprised of one or more components, preferably for oxygen removal and,optionally, pH control or other chemical adjustment to the aqueoussolutions.

[0014] These and other objects according to principles of the presentinvention are provided in apparatus for processing a workpiece,comprising:

[0015] a cleaning chamber defining a cavity for receiving the workpieceand a device opening through which said workpiece is passed into and outof the cavity;

[0016] an osmotic membrane degasifier defining a degasifier cavity, amembrane dividing the degasifier cavity into first and second parts, aaqueous solution inlet and a aqueous solution outlet associated withsaid first part to direct aqueous solution into contact with one side ofthe membrane, and a carrier gas inlet and a carrier gas outletassociated with said second part to direct carrier gas into contact withthe other side of the membrane;

[0017] and the aqueous solution outlet coupled to the cleaning chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a front elevational view of cleaning apparatus accordingto principles of the present invention;

[0019]FIG. 2 is a schematic plan view thereof;

[0020]FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG.2;

[0021]FIG. 4 is a schematic diagram thereof; and

[0022] FIGS. 5-8 show a sequence of operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] As mentioned above, the present invention has found immediateapplication in the field of semi-conductor device fabrication. However,in providing methods and apparatus for carrying out controlled immersionprocessing operations as well as providing deoxidized and/orpH-controlled aqueous solutions, the present invention is readilyadaptable to a wide range of commercially significant activities, suchas the photographic processing of plates, films and prints, and thefabrication of liquid crystal and flat panel displays, as well asarticles requiring highly refined surface finishes, such as hard diskmemory substrates. As will be seen below, the present invention will bedescribed with reference to the processing of semi-conductor wafers,although it will become readily apparent to those skilled in the artthat other types of workpieces other than semiconductor wafers andimmersion processing other than aqueous cleaning and/or rinsing ofsemiconductor wafers is also encompassed within the scope of the presentinvention.

[0024] Semiconductor wafers are typically fabricated by forming alayered series of devices integrated with an underlying semiconductorblank or so-called “prime wafer”. With the formation of each layer, thewafer in process must be polished and cleaned in preparation for thenext layering step. With ongoing changes in layer materials, new,challenging processing problems have arisen. In general, the unit costof individual wafers is increasing dramatically and, accordingly, evenpartial losses of wafers being processed result in an expensive penaltyfor the wafer fabricator. Unwanted materials, such as contaminationparticles and residues associated with via etching or metal etchingprocesses, can cause subsequent layering operations to fail. Suchresidues and contamination particles associated therewith are typicallyremoved using various solvents. The solvents are then removed with oneor more rinse solutions, and the present invention has found immediateacceptance in providing aqueous solutions (i.e., solutions whosecomposition is either exclusively or predominantly comprised of water)for use in such cleaning and especially in rinsing operations.

[0025] Increasing use is being made of device layer materials (such asaluminum/copper alloys and proposed all-copper structures) which havegreater susceptibilities to corrosion when exposed to water rinses.However, as is widely recognized, there are strong advantages inemploying aqueous solutions for wafer rinse. For example, compared tonon-aqueous rinses (i.e., rinses not predominantly comprised of water),such as isopropyl alcohol (IPA) or N-methyl pyrrolidone (NMP), aqueousrinse solutions require less investment cost, less safety precautions,are more affordable to dispose of when their useful life has expired,and for many types of popular solvents, aqueous solutions are the mosteffective rinsing agents for cleaning the wafer surfaces beingprocessed.

[0026] In developing the present invention, consideration was given tothe corrosion mechanisms typically encountered in semiconductor waferprocessing. For example, the corrosion of aluminum was studied withreference to the following oxidation/reduction reactions:

4Al→4Al³⁺+12e⁻  (Equation 1)

6H₂O+3O₂+12e⁻→12OH⁻  (Equation 2)

4Al+3O₂+6H₂O→4Al(OH)₃  (Equation 3)

4Al(OH)₃→2Al₂O₃+6H₂O  (Equation 4)

[0027] Equations 1 and 2 describe the reactions driving the formation ofcorrosion and corrosion byproducts reflected in Equations 3 and 4. Aswill be seen herein, the approach of the present invention is to removethe oxygen reactant. Further, it is observed that the corrosion ratesare affected by the pH of the aqueous solution. One objective of thepresent invention is to combine both pH control and oxygen removal toform a combined one-step treatment of the aqueous solution brought incontact with the wafers being processed.

[0028] Referring now to FIGS. 1 and 2, a wafer treatment apparatusaccording to principles of the present invention is generally indicatedat 10. Apparatus 10 includes a process chamber 12 surrounded by relatedequipment, to form a practical wafer-treating operation. As can be seenin FIG. 2, a robot load/unload area 14 is located adjacent or above theprocess chamber and includes conventional robotic placement equipment(not shown) for inserting and removing semiconductor wafers from processchamber 12. Reference numeral 16 is directed to a portion of wafertreatment apparatus 10 which includes an uninterruptable power supply(UPS) and control means, including a computer, and electronicsinput/output capability which is accessed by switches and other controls18 located on the outside of the enclosure cabinet, as can be seen, forexample, in FIG. 1.

[0029] Turning now to FIG. 3, the process chamber 12 is shown in greaterdetail. Although different processes can be carried out with chamber 12,it has found immediate application for immersion cleaning (includingrinsing and drying) of semiconductor wafers, such as wafer 22 shown inFIG. 3. Chamber 12 includes a body generally indicated at 24 comprisinga receptacle 26 and an outer, surrounding enclosure 28. Body 24 definesa hollow interior 30 which preferably is hermetically sealed andexhausted to a suitable control system.

[0030] Receptacle 26 is preferably made of quartz material or othernon-reactive material and is formed to define a wafer-receiving cavity34 having an upper opening 36 through which wafers or other workpiecespass as they are inserted and removed from cavity 34. A weir opening 38is formed adjacent the upper end of receptacle 26 and directs overflowin a manner to be described below with reference to the schematicdiagram of FIG. 4. One or more wafers 22 are supported at their bottomedge on furniture or support members 42 located adjacent a passageway 44communicating with a plenum 46 which is located beneath body 24. A fastdrain valve 48 is located at the lower end of plenum 46.

[0031] As can be seen in FIG. 3, passageway 44 connects cavity 34 withan interior volume 52 of plenum 46. A fast flow valve 60 and a slow flowvalve 62 communicate with interior 52 and are operated to fill plenum 46with an aqueous medium, preferably deionized water treated in a mannerto be described herein. Also coupled to the interior 52 of plenum 46 isa fast flow valve 66 and a slow flow valve 68, used to fill plenum 46with a chemical, such as solvents or a non-aqueous rinse solution, suchas isopropyl alcohol (IPA). In operation, plenum 46 is first filled witha desired solution, with the level eventually rising past passageway 44to enter cavity 34. The liquid level may be maintained within quartzreceptacle 26 at any step of a process or may intentionally causeoverflow to pass through overflow weir 38. Preferably, workpieces andsolutions within receptacle 26 are excited by conventional means, suchas sonic, preferably ultrasonic or megasonic transducers 102, to enhancethe cleaning or other processing operations.

[0032] An upper wall 72 of body 24 includes a recess for a conventionalsealing gasket 74. A plurality of lids, preferably two lids and mostpreferably three lids, are hingedly joined to body 24 adjacent uppersurface 72 and are selectively movable, one at a time, to sealinglyenclose the upper end 36 of receptacle 26. As will be seen herein, eachlid is operable to enclose cavity 34 to provide a wide range ofenvironments within the receptacle cavity. For example, processing lid80 hingedly connected at 82 to body 24 is closed during cleaning orother processing of wafer 22. In order to prevent condensation on thelid inner surface 84, lid 80 is provided with a blanket heater 86. It isgenerally preferred that the lid 80 confine a pressurized gas blanket ontop of the liquid surface within cavity 34. The gas blanket isintroduced into the cavity by conventional nozzle means in the processlid or cavity wall. The gas blanket can be comprised of a suitablenon-reactive purge gas, such as nitrogen, or, if desired, can becomprised of carbon dioxide so as to provide additional pH control ifthe liquid surface within cavity 34 is broken, as during a rapidcavity-filling operation. Optionally, the processing lid 80 can includeapparatus for purging ambient environment from cavity 34 preparatory toa processing operation.

[0033] Drying lid 90 is lowered to engage gasket 74 and enclose upperopening 36 of cavity 34 during wafer drying operations. Lid 90preferably includes conventional wafer drying equipment of the“MARANGONI” or surface tension gradient drying type, but other types ofdrying apparatus, such as heat lamps, super heated vapor, or spin dryingcan also be used. One example of drying lid 90 is given in U.S. Pat. No.5,634,978, the disclosure of which is incorporated by reference as iffully set forth herein.

[0034] The preferred lid 90 includes an assembly 92 of nozzles injectinga final rinse solution, preferably one having a relatively low vaporpressure, such as isopropyl alcohol, and a heated inert drying medium,such as nitrogen gas. A third, load lid 94 is used during load/unloadoperations and includes an inner surface on which wafer cassettes,carriers or other load/unload equipment may be temporarily placed.However, if working surfaces are otherwise provided, or if sufficientlycapable robotic equipment is used for loading and unloading, lid 94 maybe rendered unnecessary and can be omitted, if desired.

[0035] Referring again to FIG. 2, various components associated with thedrying equipment located in assembly 92 are identified in FIG. 2 byreference numeral 106. The components 106 are coupled by means notshown, to assembly 92 in lid 90. As mentioned, valves 60, 62 introduceaqueous media into receptacle 26. In order to provide improved controlover oxidation reactions with layered, copper-bearing structures carriedon wafer 22, the aqueous media in contact with wafer 22 is, according toone aspect of the present invention, treated by an oxygen filter in theform of an osmotic membrane degasifier indicated by reference numeral108 in FIG. 2. The aqueous media (preferably conventional deionizedwater) is passed over a semi-permeable membrane, such as membranesavailable from Hoechst Celanese for use with their LIQUI-CEL MembraneDegasifier, the osmotic membrane degasifier preferred in carrying outthe present invention. Similar osmotic membrane degasifiers may also becommercially obtained from Pall Corporation of East Hills, N.Y., underthe trade designation “SEPAREL” and W. L. Gore & Assoc. in Elkton, Md.under the trade designation “DISSOLVE”.

[0036] The aqueous media is passed over one side of the semi-permeablemembrane in degasifier 108 while a carrier fluid, preferably a gas at apre-selected temperature and pressure, is caused to flow over theopposite side of the semi-permeable membrane. The preferred carrier gas,according to the principles of the present invention, may be comprisedof one or more components and preferably carries out several purposes.First, the carrier gas “carries” or “pulls” dissolved oxygen from theaqueous media being treated. Thus, oxygen (or other dissolved gas) fromthe aqueous media is made to selectively diffuse across thesemi-permeable membrane so as to enter the carrier gas stream located onthe opposite side of the membrane. Preferably, the flow of carrier gasis set so as to maintain the highest practical diffusion rate across themembrane, preventing oxygen levels on the carrier gas side of themembrane from reaching equilibrium with the carrier gas.

[0037] Optionally, the carrier gas is selected for its ability todiffuse in a reverse direction across the semi-permeable membrane, so asto quiescently inject beneficial additives into solution in the aqueousmedia. Most preferably, the carrier gas is selected such that, upondissolving in the aqueous media it will act to alter the aqueous mediapH value in a manner which further precludes corrosion of the waferstructures. The preferred carrier gas of the present invention comprisesa mixture of two gases, one for causing dissolved oxygen in the aqueousmedia to flow across the osmotic membrane and the second to alter the pHvalue when introduced into the aqueous media. The first component can becomprised of virtually any gas or liquid other than oxygen so as tocreate the desired osmotic pressure across the membrane, and the secondcomponent most preferably comprises carbon dioxide, but may alsocomprise ammonia, nitrous oxide, nitric oxide and carbon monoxide. Thus,preferably, the carrier gas of the present invention employed for usewith semiconductor materials comprises a mixture of carbon dioxide andnitrogen gas. This carbon dioxide mixture is one example of a carriergas meeting one requirement of the present invention, that of “pulling”oxygen from the aqueous media through the semi-permeable membrane, whilepassing an effective pH modifier through the membrane in an oppositedirection.

[0038] The carrier gas can provide further functions. For example, ithas been observed that gas entrained in the aqueous media provides amore efficient coupling of agitation energy, such as sonic energy,including energy at ultrasonic and megasonic (i.e., megahertz) frequencyregimes. As pointed out above, dissolved oxygen can be a poor choice foragitation enhancement. However, with the present invention, a benign gascan be dissolved in the aqueous media, upon its passage through theosmotic membrane.

[0039] Once in solution with the aqueous media, the carbon dioxideemerging through the membrane removes OH shown in the above equations,and especially Equation 3. However, unlike carbon dioxide sparging orbubbling, potentially contaminating particles are not introduced intothe wafer-contacting aqueous media. Further advantages over spargingtechniques are also made possible by the present invention. For example,by passing through the semi-permeable membrane of the present invention,carbon dioxide is introduced into the aqueous media in a finer, i.e.,physically smaller, form. Accordingly, carbon dioxide is more completelydissolved in the aqueous media and is more quickly and thoroughly mixed.Further, with the present invention, carbon dioxide is introduced intothe aqueous media quiescently, without bubbles. In addition to slowingor otherwise impairing dissolving of the encapsulated CO₂ gas, bubblesintroduced by sparging or the like bubbling technique might be carriedto the wafer surface to form an effective barrier, at least partlyblocking intimate contact of the wafer surface with the treatingsolution.

[0040] In order to provide a wide range of control of pH values, thepreferred carrier gas, as mentioned, comprises a mixture of carbondioxide and a diluent, such as nitrogen gas, which allows the oxygentransfer rate to continue across the membrane while holding the aqueousmedia pH value at a constant level. As can be seen from the above, theCO₂ gas is introduced into the aqueous media to provide pH control. Thepresent invention also contemplates the introduction of chemicalspassing through the osmotic membrane to achieve desired objectives otherthan pH control. For example, a desired surfactant may be introduced inliquid or gaseous form in the carrier stream and, upon passing throughthe osmotic membrane, will be quiescently added to the aqueous media. Ifdesired, additional control may be provided by employing other,conventional pH control methods directly in the process chamber. Forexample, a carrier gas mixture of 4% hydrogen gas and 96% nitrogen gascan be used to provide a more reducing environment, which is less likelyto permit corrosion. As a further example, an injection apparatus can beprovided within cavity 34 to introduce a buffer or ion exchangesolution. Optionally, an acid or base drip can be added to one of thelids covering the cavity.

[0041] In addition to the above equations, consideration is also givento the increasing use of copper and copper alloys as structures layeredon semiconductor substrates. From a device manufacturer's standpoint,increased copper content provides increased conductivity and henceincreased speed of electronic operation. The demand for copper contentof copper/aluminum alloys is steadily increasing and it is possible thatmetal lines formed on semiconductor substrates may be comprised entirelyof copper metal. As is well known, even small percentages of copperundergo substantial corrosion when contacted with water containingdissolved oxygen. When such small amounts of copper (components greaterthan 1% of the total alloy) are added to aluminum, an observed galvanicreaction between copper and aluminum operates to seriously increase thecorrosion rate of the aluminum component.

3Cu_((s))+Al_((s))→Cu^(δ−)Al^(δ+)  (Equation 5)

[0042] Once the aluminum component becomes positively charged, theelectrons are attracted in the p-orbital of the rinse water O₂ molecule.By effectively removing dissolved oxygen from the aqueous media, thepresent invention eliminates these types of corrosion reactions.

[0043] It has also been observed in carrying out the present invention,that the corrosion reaction rate displays photochemical sensitivity.Attempts to quantify the photoreactivity of the various corrosionreactions have not been studied in detail, but even so, the observedphotoreactivity role is pronounced in conventional semiconductorcleaning operations. The process chamber 12 is constructed such that theinterior of receptacle 26 is sealed in a light-tight as well as anair-tight condition, using lids which carry out multiple functionsbeyond merely blocking ambient light.

[0044] As mentioned above, wafers 22 to be processed may be sprayed, butare preferably immersed in solution contained within receptacle 26. Thisprovides several advantages. Due to the chemical sensitivity ofmaterials employed, and ever tightening constraints on processparameters, management of so-called “backside” wafer contamination isbecoming increasingly important if wafer losses are to be controlled. Byproviding an immersion cleaning of wafers 22, issues of backsidecontamination are eliminated in a cost effective rapid manner, since allexposed surfaces of the wafer are cleaned simultaneously.

[0045] Further, with the present invention, dislodged particles aremanaged with greater control so as to prevent their re-introduction onthe wafer surface. For example, referring to FIGS. 2 and 4, tanks 110,112 are located adjacent process chamber 12 and are coupled to theprocess chamber with a plurality of supply and return lines. Tank 110 iscoupled to plenum 46 by a return line 116 and by a supply line 118 whichincludes a pump 120 and filter 122. A second return line 124 couplestank 110 to weir outlet 38. Tank 112 is connected to plenum 46 throughreturn line 126 and through supply line 128 associated with pump 130 andfilter 132. A second return line 134 couples tank 112 to weir outlet 38.Tanks 110, 112 have supply inlets 140, 142 to a bulk chemical source(not shown).

[0046] Referring to the bottom right corner of FIG. 4, a deionized waterinlet 150 and a carbon dioxide mixture inlet 152 are provided for theosmotic membrane degasifier 108. The carbon dioxide mixture or othercarrier gas entering inlet 152 passes across the membrane internal todegasifier 108 and exits through exhaust 154. A portion of the carriergas, along with the water introduced by inlet 150, exits through line156 which is coupled to valves 60, 62. Preferably, inlets 150, 152include temperature control (e.g., heating) capability coupled tocontroller 304. In addition to providing control of the aqueous media incavity 34, heating control at inlets 150, 152 controls the diffusionrates and bi-directional selectivity of the osmotic membrane.

[0047] Referring to the upper right-hand portion of FIG. 4, dryingequipment 106 includes a rinse agent tank 160 and a pump 162 which arecoupled to assembly 92 mounted in lid 90. As mentioned, the rinse agentpreferably comprises isopropyl alcohol. The drying gas, preferably N₂,enters through inlet 164 and is heated in heater 166, thereafter beingconducted through line 168 to assembly 92 in lid 90.

[0048] As noted above, it is preferred that all wafer-contactingchemistries are introduced into cavity 34 from plenum 46. In thisarrangement, points of entrapment are eliminated as are direct chemicalconnections to receptacle 26, thereby avoiding the attendant possibilityof mis-operation. As will be seen below, it is generally preferred thatcavity 34 be operated as a recirculating immersion process chamber aswell as an overflow immersion rinse Math. Although not preferred for thetreatment of semiconductor wafers, cavity 34 can be operated in a spraycontact or waterfall mode, with conventional nozzles located in theinterior of cavity 34 and/or the lids associated therewith.

[0049] As can be seen from the above description of FIG. 4, severalrecirculation loops are provided with the arrangement of the presentinvention and it is contemplated that the treatment apparatus maycomprise a totally closed system. However, it may also be advantageousfrom time to time to discard certain portions of the processing orrinsing agents employed and connections to an industrial waste waterdrain are provided by line 172 (exiting a manifold at the outlet ofplenum 46) and line 174 (coupled to the weir discharge 38). Connectionsto a separate solvent drain are provided by line 176 exiting plenum 46and line 178 coupled to tank weir outlet 38.

[0050] As will be appreciated from the foregoing, chamber 12 can beoperated in a number of different ways. For example, wafer treatment canbe limited to post solvent wafer rinse. However, it has been foundunnecessary to perform residue-removing solvent cleaning at a separatelocation. Rather, residue is preferably removed from the wafer usingsolvent in chamber 12, followed by a solvent-removing rinse andconcluding with a wafer drying operation. Initially, cavity 34,passageway 44 and plenum 46 are emptied, cleared of all liquids. Ifdesired, a purge gas can be employed, filling the cavity, passageway andplenum.

[0051] In preparation for a wafer transport operation, load lid 94 isopened and one or more wafers 22 are inserted in cavity 34, so as torest on furniture supports 42. In an optional pre-treating step, theempty plenum 46 is then filled with a first solvent solution, preferablytaken from tank 110 and passed through filter 122. Solvent is introducedso as to eventually fill plenum 46, passageway 44 and the interior orcavity of receptacle 26. Tank 110 preferably contains used solvent,captured from a previous secondary solvent cleaning operation, as willbe seen herein. This initial contact with the wafer causes the highestconcentration of residue and contaminating particles to enter intosolution within cavity 34. It is anticipated that, in many commercialoperations, this initial pre-treatment solution will be discarded.Depending upon the flow conditions within cavity 34, the initialpre-treating solution may also exit cavity 34 through overflow weir 38.Alternatively, cavity 34, passageway 44 and plenum 46 may be drained byline 176.

[0052] In certain instances, the pre-treatment operation may beunnecessary, in which case pump 120 is energized so as to withdraw usedsolvent from tank 110, which, after exiting filter 122, fills plenum 46and ultimately cavity 34. After a sufficient period of ultrasonicagitation, the solvent is either returned to tank 110 through line 116or is discharged to the solvent drain through line 176. It is generallypreferred during all stages of wafer cleaning that wafer 22 bemaintained fully immersed and further that cavity 34 be filled so as tocause a controlled overflow through weir 38. Overflow solvent can bereturned to tank 110 through line 124 or the overflow can be dischargedto solvent drain through line 178.

[0053] If desired, conventional particle counters 300 (see FIG. 4) suchas those commercially available from Particle Measuring Systems (PMS)located at Boulder, Colo. can be employed to monitor contents of cavity34 to aid in the decision whether to retain or discard the overflowand/or the cavity contents. Alternatively, conventional chemicalmonitoring systems 302 may be coupled to controller 304, to sample theweir overflow to detect the presence or concentration of a residuecomponent in order to provide information to controller 304 indicatingthe real time concentration of residue in solution. Such indications canbe used to detect when rinsing of solvent is complete. According to theconcentrations of residue indicated, the overflow residue can, underoperation in controller 304, be either retained in tank 110 ordiscarded. Output indications can also control any amount ofcontamination - diluting fresh chemistry that may be added to tank 110through line 140.

[0054] At the conclusion of the first cleaning stage, with the reusedsolvent being withdrawn from the plenum 46 and tank cavity 34, “cleaner”solvent in tank 112 is passed through pump 130 and filter 132 to plenum46 and the level is allowed to rise, filling cavity 34, fully immersingwafer 22 and causing a controlled overflow through weir outlet 38. Weiroverflow may be returned through line 134 to tank 112 or may bedischarged to a solvent drain through line 178. At the conclusion of thesecond stage of wafer cleaning, the wafer may be immersed, sprayed,washed or otherwise “reused” with virgin solvent from a bulk supply. Thetank cavity passageway 44 and plenum 46 are then drained of all solvent.The solvent is preferably returned to tanks 110 and/or 112 through lines116, 126 but may be discharged to a solvent drain through line 176, ifdesired.

[0055] Thereafter, wafer 22 is rinsed with an aqueous rinse solution toremove solvent from the wafer surface, wafer cavities and otherstructures carried on the wafer substrate. An aqueous media such adeionized water is processed in osmotic membrane degasifier 108, asdescribed above. A flow of deionized water enters through inlet 150 anda flow of carbon dioxide carrier gas enters the degasifier through inlet152. Oxygen enriched carrier gas exits degasifier 108 through line 154and the oxygen-depleted, pH-balanced deionized water exits degasifier108 on line 156. The aqueous solution, thus treated, may be stored onsite, if desired. Preferably, however, the aqueous solution is used ondemand, as needed. As with other solutions contacting the device beingtreated, the modified deionized water fills plenum 46, passageway 44 andcavity 34, immersing wafer 22. Preferably, a controlled overflow ismaintained through weir opening 38, being directed through a manifoldcoupled to exit line 174, thereby being passed to an industrial wastewater drain. If desired, overflow can be filtered and redirected throughpumping (not shown) to a deionized water reclaim inlet 186, althoughthis has been found to be unnecessary due to the cost efficiencies ofemploying deionized water as a rinse agent.

[0056] Turning now to FIGS. 5-8, the preferred solvent exposure will bebriefly considered. FIG. 5 shows an initial wafer contacting operationin which reused solvent from tank 110 fills cavity 34. This initialcontact with the wafer contains the majority of dissolved polymer, withpolymer concentrations substantially higher than those found in tank110. Accordingly, it may be desired to discharge the initial contactingsolvent to the solvent drain as indicated. Thereafter, the overflowsolvent is recirculated back to tank 110 and preserved for reasons ofeconomy. If desired, the solvent could also be directed to a suitablesolvent drain.

[0057] Although the solvent represented in FIG. 6 is reused andtherefore contains certain concentrations of dissolved residues, theconcentrations of residue are relatively small compared to theconcentrations obtained upon initial wafer contact as considered abovewith reference to FIG. 5. It is generally preferred that most, if notall, of the residues on the wafer be removed in the step indicated inFIG. 6, i.e., with reused solvent.

[0058] Only after the residues are removed from the surface of the waferbeing treated is cleaner solvent applied to the wafer, as indicated inFIG. 7. Use of fresh solvent eliminates the possibility of droppingdissolved polymer residue out of solution or interrupting the suspensionof polymer in solvent which is not yet filtered. The preferred purposeof introducing cleaner solvent from tank 112 is to remove dirty solventprior to recirculating the chemistry. As indicated in FIG. 7, it ispreferred to capture the “cleaner” solvent from tank 112 in tank 110,for use on the next cleaning cycle.

[0059] As will be appreciated, the chemistry now present in contact withthe wafer is cleaner than conventional dual tank bench configurations,because the volume within the tank is continually topped off with freshchemistry from a bulk source. As can be seen from the diagram of FIG. 4,it is also possible to use virgin solvent chemistry exclusively, priorto the aqueous rinse step.

[0060] Referring to FIG. 8, as a final solvent cleaning step, fresh,unused solvent is introduced and recirculated with respect to tank 112.It is preferred that solvent filling the cavity, passageway and plenumare returned to tank 112 for future use. Thereafter, the aqueous rinseand drying steps described above are carried out. During this time, tank112 is “topped off” from a bulk solvent source, if desired. As will beappreciated, fresh solvent introduced into tank 112 will have benefit ofa substantial residence time for any desired mixing, heating, or othertemperature control prior to its application in a subsequent processcycle.

[0061] In order to maintain the proper chemical component ratios of thesolvent as long as possible, the present invention allows the cleaningstep to be carried out with a minimum exhaust and purge, which mightotherwise cause a loss of quality or quantity of solvent due toevaporation or decomposition associated with oxygen and water content insurrounding air. Thus, as can be seen, the present invention providesimproved chemistry management by controlling the chemistry environmentduring a cleaning operation.

[0062] As has been noted above, certain variations and alternativearrangements are possible with the methods and apparatus according tothe principles of the present invention. If desired, other alternativearrangements can also be readily employed with the present invention,using conventional equipment and techniques. For example, operation ofthe osmotic membrane degasifier 108 can be automated using conventionaltechniques so as to minimize consumption of carrier gas. For example, asmentioned, it is preferred that a mixture of carbon dioxide and nitrogengas be used for the carrier, at a flow rate which assures adequatediffusion rates of oxygen across the membrane.

[0063] If desired, conventional metering 308 to sense dissolved oxygencan be provided on line 156 and the flow rates of the carrier gas atinlet 152 can be adjusted with control signals applied to N₂ and CO₂flow controllers 312, 314, respectively. For example, if objectionableoxygen levels are detected in line 156, the flow rate of carrier gas canbe increased in order to increase osmotic pressure, thereby withdrawinghigher rates of dissolved oxygen from incoming aqueous solution. On theother hand, if dissolved oxygen content in line 156 is sufficiently low,it may be possible to reduce the input flow of one or more carrier gascomponents and still achieve the desired levels of oxygen removal inline 156.

[0064] Further, related variations are also possible. For example, thecarbon dioxide and nitrogen components of the carrier gas can be mixedas needed and fed into inlet 152. Conventional pH meters can beincorporated in metering 308 to sense the pH of aqueous media in line156 and the CO₂ component of the carrier gas can be adjusted byoperation of flow controller 314 to attain the desired pH level. Anyundesired reaction in osmotic pressure (needed to remove dissolvedoxygen) can be effectively dealt with by independently adjusting thenitrogen gas flow component (by signals to low controller 312), sinceboth carbon dioxide and nitrogen gas components of the carrier gas areeffective in maintaining the desired osmotic pressure needed foreffective oxygen removal from the aqueous solution in degasifier 108. Ifdesired, the pH monitoring output and dissolved oxygen monitoringoutputs from metering 308 can be considered together either by anoperator or more preferably by computer controlled automation 304 tovary the flow rates of the components of carrier gas entering inlet 152.Of course, such automated control could operate to prevent aqueous mediain line 156 from entering process chamber 12 if the dissolved oxygenand/or pH levels exceed predefined control points.

[0065] As mentioned above, particle counters 300 and chemical monitoringsensors 322 of predictors indicating the concentration of dissolvedresidue can be employed in cavity 34 or in the effluent of overflowexiting weir 38. As indicated in the above discussion, it iscontemplated that automated control attention be given to the varyingconcentrations of contaminant particles and residue levels in cavity 34,and that control steps be taken to segregate (preferably discard)materials containing unacceptably high concentrations of contaminantparticles and/or dissolved residue.

[0066] Contaminant levels (either particles or dissolved residue) can beestimated based on their residence time in contact with the wafer orother workpieces immersed within cavity 34. For example, considerationis given to the fact that the material filling cavity 34 be inputted inthe plenum 46 at a rate so as to assure a desired rate of overflowpassing through overflow weir 38. Overflow materials initially appearingat weir 38 can, for an initial period of time, be diverted away from arecirculation loop or storage container and thus be prevented fromcoming into contact with lesser-contaminated solution.

[0067] However, using conventional automation techniques, greaterefficiencies can be obtained by directly monitoring the contaminationlevels within cavity 34 and/or effluent from overflow weir 38. Particlecounters and/or automated chemical monitors of dissolved residue can beemployed to provide a more efficient use of solution by preventing theunnecessary disposal of solution initially contacting the wafer surface.In this manner, greater flexibility of operation is possible and wafersof differing compositions and surface properties can be accommodatedwith a single routine production schedule.

[0068] Further, with the introduction of automated metering and othercontrols, it may be possible to consider a refurbishing of treatmentmaterials employed in the process chamber. For example, decisions can bemade based upon the contaminant levels (either particles in solution ordissolved chemistries) as to whether it is cost effective to attempt toreclaim the solution in question. For example, it may be observed thatsolvents and rinse solutions contain acceptable levels of chemicalcomponents, but unfortunately carry unacceptably high levels ofcontaminant particles. The solutions in question can be directed throughconventional filtering equipment and retested to certify theiracceptability for re-introduction in subsequent processing stages. Itmay also be possible to perform the same reclamation, by chemicallytreating the solution in question so as to remove or reduce unwanteddissolved chemistries.

[0069] Automated instrumentation can also take into account the need formake-up of solutions flowing through tanks 110 or 112, for example.Calculations can be made as to the net effect on ultimate contaminatelevels and it may be possible from time to time to prevent theunnecessary discarding of process solutions by diluting with freshchemistries, thereby providing savings relating not only to the cost ofreplacement solutions but also of waste handling. It will be appreciatedby those skilled in the art that such automated instrumentation can beprovided using conventional techniques, in a space-efficient mannerwhich would not contribute considerably to the space requirements forthe processing equipment.

[0070] It will be readily appreciated by those skilled in the art thatthe oxygen filter (e.g., osmotic membrane degasifier), along withoptional automated controls, can be used in stand-alone mode to providea stored quantity of treated aqueous material. Further, the oxygenfilter can be incorporated in arrangements other than those shownherein. For example, conventional wafer polishing operations can benefitfrom the incorporation of the oxygen filter according to principles ofthe present invention, and it will be appreciated in this regard thatsubstantial reduction of wafer handling is thereby made possible. Ifdesired, further advantages may be obtained by combining the oxygenfilter and process chamber of the present invention, incorporating thecombination, for example, in existing wafer processing operations.

[0071] If desired, variations in the process chamber are alsocontemplated by the present invention. As mentioned above, waferprocessing benefits from a light-tight closed environment and aflexibility of operation and reduction in wafer handling has beenachieved by incorporating a plurality of different lid arrangements witha common receptacle. It is possible, however, to adapt the receptaclefor continuous, rather than batch operations. For example, a conveyorbelt can be made to pass through the process receptacle and can includedepressed portions for immersing articles carried on the conveyor beltbeneath fluid levels maintained within the receptacle. Such arrangementsmay be particularly attractive for photographic operations, for example.

[0072] The drawings and the foregoing descriptions are not intended torepresent the only forms of the invention in regard to the details ofits construction and manner of operation. Changes in form and in theproportion of parts, as well as the substitution of equivalents, arecontemplated as circumstances may suggest or render expedient; andalthough specific terms have been employed, they are intended in ageneric and descriptive sense only and not for the purposes oflimitation, the scope of the invention being delineated by the followingclaims.

What is claimed is:
 1. Apparatus for processing a workpiece, comprising:a treatment chamber defining a cavity for receiving the workpiece and adevice opening through which said workpiece is passed into and out ofthe cavity; an osmotic membrane degasifier defining a degasifier cavity,a membrane dividing the degasifier cavity into first and second parts, aaqueous solution inlet and a aqueous solution outlet associated withsaid first part to direct aqueous solution into contact with one side ofthe membrane, and a carrier fluid inlet and a carrier fluid outletassociated with said second part to direct carrier fluid into contactwith the other side of the membrane; and the aqueous solution outletcoupled to the treatment chamber.
 2. The apparatus of claim 1 furthercomprising a plenum coupled to the treatment chamber and defining amixing chamber coupled to the aqueous solution outlet.
 3. The apparatusof claim 1 further comprising a chemical opening for introducing aprocessing chemical into the mixing chamber.
 4. The apparatus of claim 1further comprising a plurality of covers hingedly connected to saidtreatment chamber to selectively cover said device opening.
 5. Theapparatus according to claim 4 further comprising fluid blanket meansfor inserting a gas blanket enclosed within said cavity.
 6. Theapparatus according to claim 5 wherein said gas blanket means isdisposed in one of said covers.
 7. The apparatus according to claim 5wherein said gas blanket is at least partially comprised of carbondioxide gas.
 8. The apparatus of claim 4 wherein at least one of saidcovers is light blocking.
 9. The apparatus of claim 4 wherein one ofsaid covers includes a heater means to prevent condensation.
 10. Theapparatus of claim 4 wherein one of said covers includes means forinjecting a rinse agent into said chamber.
 11. The apparatus of claim 10wherein said one cover further includes means for directing a drying gasinto said chamber.
 12. The apparatus of claim 1 wherein said treatmentchamber includes a cavity wall defining said cavity, said apparatusfurther comprising agitation means coupled to at least one of saidcavity wall and said aqueous solution.
 13. The apparatus according toclaim 12 wherein said agitation means comprises ultrasonic transducermeans coupled to at least one of said cavity wall and said aqueoussolution.
 14. The apparatus according to claim 12 wherein said agitationmeans comprises megahertz frequency transducer means coupled to at leastone of said cavity wall and said aqueous solution to impart agitationenergy thereto.
 15. The apparatus of claim 1 wherein: said treatmentchamber further defines an overflow weir.
 16. The apparatus of claim 15further comprising: a storage tank; and means for coupling said weir tosaid storage tank.
 17. The apparatus of claim 16 further comprising: oneof said treatment chamber and said plenum defining a return outlet; andmeans for coupling said return outlet to said storage tank.
 18. Theapparatus of claim 17 further comprising a plenum coupled to thetreatment chamber, said plenum defining a mixing chamber coupled to theaqueous solution outlet and containing said return outlet.
 19. Theapparatus of claim 1 further comprising: oxygen sensor means for sensingthe oxygen content in the aqueous solution outlet; and flow controlmeans coupled to said sensor and responsive thereto for controlling theflow of carrier fluid at said carrier fluid inlet.
 20. The apparatus ofclaim 19 wherein said carrier fluid comprises a composition of first-andsecond gases and said flow control means comprises means for controllingthe flow of each of said components.
 21. The apparatus according toclaim 1 further comprising particle counting means disposed in saidtreatment chamber for counting the particles transferred from saidworkpiece to said aqueous fluid in said cavity.
 22. A method fortreating a workpiece with an aqueous solution, comprising: providing acarrier fluid comprising at least one component; passing said aqueoussolution and said carrier fluid through an osmotic membrane degasifierhaving a membrane, so as to draw oxygen from said aqueous solutionthrough said membrane to said carrier fluid; providing a treatmentchamber; at least partly filling said treatment chamber with saidaqueous solution from said osmotic membrane degasifier; and at leastpartly immersing said workpiece in said aqueous solution.
 23. The methodof claim 22 wherein said step of passing said carrier fluid through saidosmotic membrane degasifier also passes carrier fluid through saidmembrane, introducing at least one component of said carrier fluid intosaid aqueous solution so as to control the pH of said aqueous solution24. The method of claim 23 wherein said carrier fluid includes carbondioxide.
 25. The method of claim 22 further comprising the steps of:providing a treatment chamber defining a cavity for receiving theworkpiece; inserting the workpiece into the cavity; and filing thecavity with said aqueous solution so as to immerse said workpiece insaid aqueous solution.
 26. The method of claim 25 further comprising thesteps of: providing a plenum defining a mixing chamber coupled to saidtreatment chamber; and the step of filling the cavity with said aqueoussolution comprises the step of passing aqueous solution through saidmixing chamber prior to entering said cavity.
 27. The method accordingto claim 25 further comprising the step of sealing said cavity with alight-tight cover.
 28. The method according to claim 25 furthercomprising the step of enclosing the cavity with a heated cover.
 29. Themethod according to claim 25 further comprising the step of enclosingthe cavity with a cover and introducing a gas blanket in said cavity.30. The method according to claim 29 wherein said gas blanket is atleast partly comprised of carbon dioxide.
 31. The method according toclaim 25 further comprising the step of providing a cover to enclosesaid cavity and injecting a rinse agent from said cavity into saidtreatment chamber.
 32. The method according to claim 25 furthercomprising the steps of providing a cover to enclose said cavity,emptying said cavity, and directing a drying gas from said cover intosaid treatment chamber.
 33. The method of claim 22 further comprisingthe step of agitating the aqueous solution to enhance the treatment ofworkpieces therein.
 34. The method according to claim 33 wherein saidagitating step comprises exciting said aqueous solution with anultrasonic frequency.
 35. The method according to claim 33 wherein saidagitating step comprises exciting said aqueous solution with sonicenergy in the megahertz frequency range.
 36. The method according toclaim 22 further comprising the step of providing an overflow weir insaid treatment chamber and filling said treatment chamber with saidaqueous solution so as to overflow a portion of said aqueous solutionthrough said weir.
 37. The method according to claim 36 furthercomprising the steps of providing a storage tank and coupling the flowfrom said weir to said storage tank.
 38. The method according to claim22 further comprising the step of monitoring the oxygen content of saidaqueous solution from said osmotic membrane degasifier.
 39. The methodaccording to claim 38 further comprising the step of controlling theflow of carrier fluid through said osmotic membrane degasifier inresponse to the oxygen level sensed in said aqueous solution from saidosmotic membrane degasifier.
 40. The method according to claim 39wherein the step of providing a carrier fluid comprises the step ofproviding a plurality of carrier fluid components and mixing saidcarrier fluid components together to form said carrier fluid.
 41. Themethod according to claim 40 wherein the step of controlling the flow ofcarrier fluid entering said osmotic membrane degasifier comprises thestep of individually controlling the carrier fluid components which aremixed together to form said carrier fluid.
 42. The method according toclaim 22 wherein said step of contacting the workpiece with said aqueoussolution from said osmotic membrane degasifier comprises immersing theworkpiece in said aqueous solution.
 43. The method according to claim 22wherein said step of contacting the workpiece with said aqueous solutionfrom said osmotic membrane degasifier comprises spraying the workpiecewith said aqueous solution.
 44. The method according to claim 22 whereinsaid step of contacting the workpiece with said aqueous solution fromsaid osmotic membrane degasifier comprises passing said aqueous solutionover the workpiece.
 45. A method for treating opposed major surfaces ofa semiconductor device, comprising: providing a treatment chamberdefining a cavity for receiving the semiconductor device; providing acarrier fluid; providing an aqueous solution; inserting thesemiconductor device into the cavity; passing said aqueous solution andsaid carrier fluid through an osmotic membrane degasifier having amembrane so as to draw oxygen from said aqueous solution through saidmembrane to said carrier fluid and so as to introduce carrier fluidthrough said membrane, into said aqueous solution so as to control thepH of said aqueous solution; and contacting said semiconductor waferwith aqueous solution from said osmotic membrane degasifier.
 46. Themethod of claim 45 further comprising the step of drying the saidsemiconductor device by emptying the cavity of said aqueous fluid andpassing heated fluid over the surfaces of said semiconductor device. 47.The method of claim 46 wherein said step of drying said semiconductordevice further comprises the step of spraying a rinse chemical on themajor surfaces of said semiconductor device.
 48. The method according toclaim 45 further comprising the steps of: providing a process cover withheater means for heating the process cover; providing a drying coverwith means for directing a stream of drying gas; providing saidtreatment chamber with a device opening through which said semiconductordevice is passed into and out of said cavity; covering said deviceopening with said process cover during treatment of said semiconductordevice; and withdrawing said process cover from said device opening andcovering said device opening with said drying cover during drying ofsaid semiconductor device.
 49. The method according to claim 45 furthercomprising the step of sonically exciting at least one of said treatmentchamber and sid aqueous solution with sonic energy in one of saidultrasonic and said megahertz frequency ranges.
 50. The method accordingto claim 45 further comprising the steps of providing an overflow weirand filling said cavity with aqueous solution so as to immerse saidsemiconductor device with said aqueous solution and so as to overflowaqueous solution through said weir.
 51. The method according to claim 50further comprising the steps of providing a storage tank and couplingthe overflow through said weir to said storage tank.
 52. The methodaccording to claim 48 further comprising the steps of monitoring theoxygen content of said aqueous solution from said osmotic membranedegasifier.
 53. The method according to claim 52 further comprising thestep of controlling the flow of carrier fluid through said osmoticmembrane degasifier in response to measurements of oxygen in saidaqueous solution.
 54. The method according to claim 53 wherein saidcarrier fluid is comprised of a plurality of carrier fluid componentswhich are mixed together to comprise said carrier fluid.
 55. The methodaccording to claim 54 wherein said step of controlling the flow ofcarrier fluid comprises the step of individually controlling the flow ofcarrier fluid components mixed together and inputted into said osmoticmembrane degasifier.
 56. The method of claim 45 further comprising thestep of providing said carrier fluid with a carbon dioxide component.57. The method according to claim 45 further comprising the steps ofcounting particles transferred from said semiconductor device to saidaqueous solution.
 58. The method according to claim 56 furthercomprising the step of withdrawing at least a portion of said aqueoussolution from said receptacle in response to said counting of particlestransferred from said semiconductor device to said aqueous solution. 59.The method of claim 50 further comprising the steps of: providing aplenum defining a mixing chamber coupled to said treatment chamber; andthe step of filling the cavity with said aqueous solution comprises thestep of passing aqueous solution through said mixing chamber prior toentering said cavity.
 60. The method according to claim 45 furthercomprising the step of enclosing the cavity with a cover and introducinga gas blanket in said cavity.
 61. The method according to claim 60wherein said gas blanket is at least partly comprised of carbon dioxide.62. Apparatus for processing a semiconductor device, comprising: atreatment chamber defining a cavity for receiving the semiconductordevice with a device opening through which said semiconductor device ispassed into and out of the cavity; a plenum coupled to the treatmentchamber and defining a mixing chamber including a aqueous solution inletopening for introducing aqueous solution into the mixing chamber and anonaqueous solvent opening for introducing a nonaqueous solvent into themixing chamber; and an osmotic membrane degasifier defining a degasifiercavity, a membrane dividing the degasifier cavity into first and secondparts, an aqueous solution inlet and a aqueous solution outletassociated with said first part, and a carrier fluid inlet and a carrierfluid outlet associated with said second part, with the aqueous solutionoutlet coupled to the aqueous solution inlet opening of said plenum. 63.The apparatus of claim 62 further comprising a plurality of covershingedly connected to said treatment chamber to selectively cover saiddevice opening.
 64. The apparatus of claim 63 wherein at least one ofsaid covers is light blocking.
 65. The apparatus of claim 63 wherein oneof said covers includes a heater means to prevent condensation.
 66. Theapparatus of claim 63 wherein one of said covers includes means forinjecting a rinse agent into said chamber.
 67. The apparatus of claim 66wherein said one cover further includes means for directing a drying gasinto said chamber.
 68. The apparatus of claim 62 wherein said treatmentchamber includes a cavity wall defining said cavity, said apparatusfurther comprising sonic agitation means coupled to one of saidcavity~wall and said aqueous solution.
 69. The apparatus of claim 62wherein said treatment chamber further defines an overflow weir.
 70. Theapparatus of claim 69 further comprising: a storage tank; and means forcoupling said weir to said storage tank.
 71. The apparatus of claim 70further comprising: one of said treatment chamber and said plenumdefining a return outlet; and means for coupling said return outlet tosaid storage tank.
 72. The apparatus of claim 71 further comprising aplenum coupled to the treatment chamber, said plenum defining a mixingchamber coupled to the aqueous solution outlet and containing saidreturn outlet.
 73. The apparatus of claim 62 further comprising: oxygensensor means for sensing the oxygen content in the aqueous solutionoutlet; and flow control means coupled to said sensor and responsivethereto for controlling the flow of carrier fluid at said carrier fluidinlet.
 74. The apparatus of claim 73 wherein said carrier fluidcomprises a composition of first-and second fluids and said flow controlmeans comprises means for controlling the flow of each of said fluidcomponents.
 75. The apparatus according to claim 62 further comprisingparticle counting means disposed in said treatment chamber for countingthe particles transferred from said workpiece to said aqueous fluid insaid cavity.
 76. A method for cleaning opposed major surfaces of asemiconductor device, comprising: providing a cleaning chamber defininga cavity or receiving the semiconductor device; inserting thesemiconductor device into the cavity; filling the cavity with a firstsolvent so as to immerse said semiconductor device in said first solventwhile exciting said chamber with ultrasonic energy so as to transmitsaid ultrasonic energy through said first solvent to said semiconductordevice; emptying said cavity of said first solvent; filling the cavitywith a second solvent so as to immerse said semiconductor device in saidsecond solvent while exciting said chamber with ultrasonic energy so asto transmit said ultrasonic energy through said second solvent to saidsemiconductor device; emptying said cavity of said second solvent;providing an aqueous solution; providing a carrier fluid containingcarbon dioxide passing said aqueous solution and said carrier fluidthrough an osmotic membrane degasifier having a membrane, so as to drawoxygen from said aqueous solution through said membrane to said carrierfluid and so as to introduce carbon dioxide gas through said membrane,into said aqueous solution so as to control the pH of said aqueoussolution. filling the cavity with a aqueous solution from said osmoticmembrane degasifier so as to immerse said semiconductor device in saidaqueous solution while exciting said chamber with ultrasonic energy soas to transmit said ultrasonic energy through said aqueous solution tosaid semiconductor device; emptying said cavity of said aqueoussolution: drying the major surfaces of conductor device; and removingsaid semiconductor device from said cavity.
 77. The method of claim 76wherein said step of drying the said semiconductor device comprises thestep of passing heated fluid over the surfaces of said semiconductordevice.
 78. The method of claim 76 wherein said step of drying saidsemiconductor device further comprises the step of spraying a rinseagent on the major surfaces of said semiconductor device.
 79. The methodaccording to claim 76 further comprising the steps of: providing aprocess cover with heater means for heating the process cover; providinga drying cover with means for directing a stream of drying gas;providing said cleaning chamber with a device opening through which saidsemiconductor device is passed into and out of said cavity; coveringsaid device opening with said process cover during rinsing of saidsemiconductor device; and withdrawing said process cover from saiddevice opening and covering said device opening with said drying coverduring cleaning of said semiconductor device.
 80. The method of claim 76further comprising the steps of: providing a plenum defining a mixingchamber coupled to said treatment chamber; and the step of filling thecavity with said aqueous solution comprises the step of passing aqueoussolution through said mixing chamber prior to entering said cavity. 81.The method according to claim 76 further comprising the step of sealingsaid cavity with a light- tight seal.
 82. The method according to claim76 further comprising the step of enclosing the cavity with a heatedlid.
 83. The method according to claim 80 further comprising the step ofwithdrawing at least a portion of said first solvent from said cavityand passing said withdrawn portion of said first solvent through saidmixing chamber for reintroduction into said cavity.
 84. The methodaccording to claim 80 further comprising the step of withdrawing atleast a portion of said second solvent from said cavity and passing saidwithdrawn portion of said second solvent through said mixing chamber forreintroduction into said cavity.
 85. The method according to claim 80further comprising the step of withdrawing at least a portion of saidaqueous solution from said cavity and passing said withdrawn portion ofsaid aqueous solution through said mixing chamber for reintroductioninto said cavity.
 86. The method according to claim 76 furthercomprising the step of providing an overflow weir in said treatmentchamber and filling said treatment chamber with said aqueous solution soas to overflow a portion of said aqueous solution through said weir. 87.The method according to claim 86 further comprising the steps ofproviding a storage tank and coupling the flow from said weir to saidstorage tank.
 88. The method according to claim 76 further comprisingthe step of monitoring the oxygen content of said aqueous solution fromsaid osmotic membrane degasifier.
 89. The method according to claim 88further comprising the step of controlling the flow of carrier fluidthrough said osmotic membrane degasifier in response to the oxygen levelsensed in said aqueous solution from said osmotic membrane degasifier.90. The method according to claim 89 wherein the step of providing acarrier fluid comprises the step of providing a plurality of carrierfluid components and mixing said carrier fluid components together toform said carrier fluid.
 91. The method according to claim 90 whereinthe step of controlling the flow of carrier fluid entering said osmoticmembrane degasifier comprises the step of individually controlling thecarrier fluid components which are mixed together to form said carrierfluid.
 92. The method according to claim 76 wherein said step ofcontacting the workpiece with said aqueous solution from said osmoticmembrane degasifier comprises immersing the workpiece in said aqueoussolution.
 93. The method according to claim 76 wherein said step ofcontacting the workpiece with said aqueous solution from said osmoticmembrane degasifier comprises spraying the workpiece with said aqueoussolution.
 94. The method according to claim 76 wherein said step ofcontacting the workpiece with said aqueous solution from said osmoticmembrane degasifier comprises passing said aqueous solution over theworkpiece.